Bending machine

ABSTRACT

The invention relates to a bending press ( 3 ), in particular a press brake, comprising a machine frame ( 7 ) and pressing bars ( 13, 16 ), and tool holders ( 19, 20 ) and bending tools ( 4 ) arranged or formed on the pressing bars ( 13, 16 ) in the form of a bending punch ( 5 ) or a bending die ( 6 ), wherein a receiving portion ( 35 ) of the bending tools ( 4 ) is accommodated in a receiving groove ( 34 ) of the tool holder ( 19, 20 ). The tool holder ( 19, 20 ) and a driver device ( 41 ) assigned to the bending tool ( 4 ) are designed as a linear motor, as a result of which the bending tool ( 4 ) can be positioned in a direction ( 32 ) that is parallel to a bending edge ( 31 ).

The invention relates to a bending press, as described in claim 1.

From the prior art a plurality of different devices are known which enable the automatic fitting of bending tools on a bending press. Mostly, a manipulation robot, or backstop unit is used for fitting the bending tools onto the bending machine. In this case the bending tool is removed by means of the manipulation robot or the backstop unit from the tool store and positioned in the tool holder according to the tool holder system. It is possible here for the bending tool to be pushed along the longitudinal alignment of the tool holder into the latter and thereby positioned. A further option is to insert the bending tool with the manipulation robot or the backstop unit directly in its end position in a direction perpendicular to the longitudinal alignment, wherein a catching mechanism needs to be provided in the bending tool for inserting the tool.

Said embodiments have the disadvantage that the manipulation robot or the backstop unit need to have a large operating range in order to be able to position the bending tools along the whole longitudinal extension of the tool holder. Because of this the manipulation robot or backstop unit are very complex and very heavy. Furthermore, the bending tools can only be removed individually from the tool store and inserted into the tool holder, which is time-consuming.

Furthermore, devices are known in which a bending tool is inserted by a manipulation device into the tool store and is then positioned by means of a spindle drive or by means of a rack in longitudinal direction of the tool store.

Said embodiments have the disadvantage that a spindle drive or a rack are complex to produce and thus expensive to purchase. Furthermore, for such drive methods separate holding constructions are used for holding the bending tools, thereby further increasing the complexity of the production facility.

The underlying objective of the present invention is to create a bending press which comprises an improved device for fitting tools.

Said objective of the invention is achieved by the measures according to claim 1.

According to the invention a bending press, in particular a press brake, comprises a machine frame and pressing bar as well as tool holders and bending tools arranged or formed on the pressing bar in the form of a bending punch or a bending die, wherein a receiving portion of the bending tools is mounted in a receiving groove of the tool holder. The tool holder and a driver device assigned to the bending tool are designed as linear motors, whereby the bending tool can be positioned in a direction parallel to a bending edge.

An advantage of the configuration of the bending press according to the invention is that no external device needs to be provided for displacing the bending tool. Furthermore, no additional moving parts are required which are subject to wear. Thus the bending tools can be moved as simply and efficiently as possible in the tool holder. Furthermore, an embodiment in the form of a linear motor has the advantage that individual bending tools can be displaced independently of one another and thus the flexibility of the bending press can be increased.

Furthermore, it can be advantageous to design the tool holder as a long stator. It is an advantage in this case that in this way the costs of forming a linear motor can be kept as low as possible. In particular, the individual bending tools do not have to be provided with windings.

Furthermore, the driver device can be designed as a shuttle, which is guided in the tool holder and can be coupled to the receiving portion of the bending tool. It is an advantage in this case that not every individual bending tool has to be fitted with a permanent magnet, but only the shuttle, which can be coupled to the bending tool, needs to comprise the permanent magnets. In this way the manufacturing costs of the bending press can be kept low.

Furthermore, it is possible for the shuttle to be coupled by means of retractable pins to the receiving portion of the bending tool. It is an advantage in this case that the shuttle can thus be coupled simply with the bending tool to be displaced.

Alternatively, the driver device can be designed in one piece with the receiving portion of the bending tool. If the driver device is formed directly in the bending tool this has the advantage that each of the bending tools can be displaced individually and independently of one another. Furthermore, no additional component needs to be provided in the form of a shuttle in order to displace the bending tools.

According to one development it is possible to arrange a cleaning shuttle in the tool holder which is designed for cleaning the receiving groove of the tool holder, wherein the cleaning shuttle also acts as a linear motor with the tool holder. It is an advantage hereby that by means of the cleaning shuttle the tool holder can be freed of dirt and thus bending tools can be mounted easily in the tool holder.

Furthermore, it can be advantageous to arrange permanent magnets in the driver device. It is an advantage here that permanent magnets can be arranged easily in the driver device, wherein the linear motor is designed as a synchronizer motor.

Furthermore, it is possible to arrange a three-phase winding system in the area of the receiving groove of the tool holder, wherein the winding system is controlled by a control device such that individual bending tools mounted in the tool holder can be displaced independently of one another. It is an advantage hereby that the winding system is mounted as far as possible in a space-saving manner and so as to be unsusceptible to mechanical damage in the tool holder.

Furthermore, the winding system can be arranged on a groove base of the receiving groove and the permanent magnets are arranged on an end side of the receiving portion of the bending tool. It is an advantage hereby that the linear motor can be designed to be as simple as possible.

According to one alternative variant it is possible that the winding system is formed on at least one side face of the receiving groove and that the permanent magnets are arranged on at least one side face of the receiving portion of the bending tool. It is an advantage here that no vertical force component is exerted on the bending tool by the winding system.

According to one advantageous development the winding system is formed on both side faces of the receiving groove and the permanent magnets are arranged on both side faces of the receiving portion of the bending tool, wherein the two winding systems are arranged to be symmetrical to a central plane of the tool holder. In particular, by means of such an embodiment the force applied by the winding system in the bending tool is lifted due to the symmetry, whereby the sliding friction between the bending tool and the tool holder can be reduced. In particular, in this way the bending tools can be displaced more easily in the tool holder.

Furthermore, it can be advantageous if the winding system extends over the whole length of the tool holder. In this way the bending tools can be displaced over the whole length of the tool holder.

Furthermore, a sensor can be formed which is provided for detecting the position of the bending tool. By means of the sensor the position of the individual bending tools can be detected or determined by using a control.

Furthermore, the sensor can be arranged on the tool holder. It is an advantage hereby that only one sensor needs to be provided which is used for all of the bending tools and that it is not necessary to provide a single sensor for each bending tool on the bending tool.

Furthermore, a clamping jaw can be provided in the bending tool, which clamping jaw can be released by the magnetic field of the winding system. It is an advantage hereby that by means of the clamping jaw the bending tool can be secured against unintentional displacement in the tool holder. In particular, it is an advantage that the clamping jaw can be released by the magnetic field of the winding system. Thus no additional actuating or activating mechanism is required to release the clamping jaw.

According to one development it is possible for the tool holder to comprise an attachment strip which is arranged outside the receiving groove and in which the winding system is integrated. It is an advantage hereby that the attachment strip can be attached easily onto the tool holder and thus the winding system can be arranged on the tool holder if necessary so as to be removable.

For a better understanding of the invention the latter is explained in more detail with reference to the following figures.

In a much simplified, schematic representation:

FIG. 1 is a front view of a production facility with a bending press;

FIG. 2 is a schematic cross-sectional representation of a first embodiment of a bending tool with tool holder;

FIG. 3 is a schematic cross-sectional representation of a second embodiment of a bending tool with tool holder;

FIG. 4 is a schematic cross-sectional representation of a third embodiment of a bending tool with tool holder;

FIG. 5 is a schematic cross-sectional representation of a fourth embodiment of a bending tool with tool holder;

FIG. 6 is a schematic cross-sectional representation of a fifth embodiment of a bending tool with tool holder;

FIG. 7 is a schematic cross-sectional representation of a sixth embodiment of a bending tool with tool holder;

FIG. 8 is a schematic longitudinal cross-section of an embodiment of a bending tool with tool holder.

First of all, it should be noted that in the variously described exemplary embodiments the same parts have been given the same reference numerals and the same component names, whereby the disclosures contained throughout the entire description can be applied to the same parts with the same reference numerals and same component names. Also details relating to position used in the description, such as e.g. top, bottom, side etc. relate to the currently described and represented figure and in case of a change in position should be adjusted to the new position.

FIG. 1 shows an embodiment variant of a production facility 1 for freely bending workpieces 2 to be made from sheet metal in a schematically simplified representation.

The production facility 1 comprises a bending press 3, in particular a press brake, for the production of workpieces 2 or parts between bending tools 4 which are adjustable relative to one another, such as a bending punch 5 and bending die 6. The bending punch 5 can also be denoted as an upper tool and the bending die 6 can also be denoted as a lower tool.

A machine frame 7 of the bending press 3 comprises for example a base plate 8, on which vertically rising side panels 9, 10 can be arranged, which are aligned spaced apart from one another in transverse direction and parallel to one another. The latter are preferably connected to one another by a solid transverse cross-tie 11, made for example from a sheet metal molding, at their end areas spaced apart from the base plate 8.

The side panels 9, 10 can be designed to be approximately C-shaped to form a free space for shaping the workpiece 2, wherein a fixed pressing bar 13 can be secured onto front end faces 12 of sides of the side panels 9, 10 close to the base, in particular standing on the base plate 8. Said pressing bar 13 can also be referred to as a table bar. On sides of front end faces 14 remote from the base plate 8 in linear guides 15 an additional pressing bar 16 adjustable relative to the pressing bar 13 forming the table bar, in particular a pressure bar, can be mounted guidably.

On opposite, parallel end faces 17, 18 of the two pressing bars 13, 16 tool holders 19, 20 can be arranged or formed for fitting with bending tools 4.

The shown bending press 3 comprises as a drive assembly 21 for the adjustable pressing bar 16, namely the pressing bar, at least one, here two drive means 22, which are supplied e.g. with electrical power from a power network 23 or by a hydraulic circuit and can additionally also be line-connected to the control device 24. For example the operation of the bending press 3 is controlled by means of an input terminal 25 line-connected to the control device 24.

The drive means 22 can be for example electric motor spindle drives 26, as generally known, by which adjusting means 27 for the reversible adjusting movement of the upper pressing bar 16 formed by the pressing bar are connected to the latter, for example drive-connected. Independently of this it would also be possible to provide the drive means 22 as hydraulically and/or pneumatically activated adjusting means. Here cylinder piston arrangements can be used. Other drive means would also be possible such as e.g. eccentric drives, toggle drives, rack drives etc.

All of the above embodiments and individual features in the description of the figures have been given to describe an example of a production facility 1 and bending press 3, which can be referred to in the following part of the description of the figures which is essential to the invention. All of the individual features described are therefore not absolutely necessary for the embodiment according to the invention and can be omitted or replaced by other features to obtain a functioning bending press 3.

Furthermore, it is shown here in simplified form that the bending tools 4, in particular the bending punch 5 and/or the bending die 6, can comprise recesses 28, 29 for manipulating the latter. Manipulating the bending tool 4 means here that the latter or its bending punch 5 and/or bending die 6 is removed automatically by means of a manipulation device from a tool store and moved automatically to an insertion position 30 of the tool holders 19, 20 of the pressing bar 13, 16 and is inserted and clamped there. The insertion position 30 can be defined in any position of the tool holder 19, 20. Furthermore, it is also possible that the insertion position 30 is selected differently according to the actual requirements. It is also possible to refer here to a tool changing system, by means of which the changing processes can be performed with the necessary system parts.

Said manipulation device can be designed in the form of a manipulator which is used for example for the workpiece handling. Furthermore, it is possible for the manipulation device to be formed for example by a backstop unit which is designed to also take on manipulation activities. In addition to this and additional possible embodiment variants it is also possible that a manipulator designed for handling bending tools is used as a manipulation device.

The bending tools 4 have a bending edge 31 which extends in longitudinal direction of the bending tool 4. The bending edge 31 also defines the contour of the bending line on the workpiece 2 to be bent. The bending tools 4 are mounted in the tool holder 19, 20 such that the latter can be displaced in a direction parallel to the bending edge 31 as necessary. In particular the bending tools 4 can be displaced over the whole length 33 of the tool holder 19, 20.

FIG. 2 shows a cross-sectional view of an embodiment of the bending tool 4 and the tool holder 19, 20, wherein the same reference numerals and component names are used for the same parts as in the preceding FIG. 1. To avoid unnecessary repetition reference is made to the detailed description of the preceding FIG. 1.

As shown in FIG. 2 the tool holder 19, 20 can comprise a receiving portion 34 which receiving portion 34 can be designed for example in the form of a U-shaped groove. Corresponding with this the bending tool 4 can comprise a receiving portion 35 which is designed for mounting in the receiving groove 34. In particular, the effect of a linear motor 36 is created between the bending tool 4 and tool holder 19, 20 by suitable technical means. By providing the linear motor 36 the bending tool 4 can be displaced in a direction 32 parallel to the bending edge 31. It is not necessary for additional mechanically movable components to be installed into the tool holder 19, 20 in order to displace the bending tool 4.

For example, as shown in FIG. 2, the linear motor 36 can be designed in the form of a long stator-linear motor, wherein a winding system 36 is arranged in the tool holder 19, 20. The winding system 37 can be arranged for example in the area of the groove base 38 of the receiving groove 34.

Furthermore, one or more permanent magnets 39 can be arranged in the bending tool 4, which cooperate with the winding system 37 to produce a magnetic force. Such a structure with a winding system 37 as a stator and permanent magnets 39, which are integrated into the rotor, is denoted as a synchronous linear motor.

In a further embodiment variant it is also possible to provide an asynchronous linear motor. In such an embodiment variant instead of the permanent magnets 39 windings are integrated into the rotor, in which currents are induced.

Furthermore, the winding system 37 can extend over the whole length 33 of the tool holder 19, 20, wherein a tool store is arranged next to the tool holder 19, 20 in which the bending tools 4 are displaced. Furthermore, in the tool store a winding system can also be arranged which is used for transporting the bending tools 4 in the tool store.

As shown in FIG. 2 the permanent magnets 39 can be arranged on an end side 40 of the receiving portion 35 of the bending tool 4. The part of the receiving portion 35, in which the permanent magnets 39 are inserted, can also be referred to as a driver device 41.

As shown in FIG. 2 it is possible for the winding system 37 to be embedded directly into the tool holder 19, 20.

FIG. 3 shows an alternative embodiment variant of the tool holder 19, 20, wherein the same reference numerals and component names are used for the same parts as in the preceding FIGS. 1 and 2. To avoid unnecessary repetition reference is made to the detailed description of the preceding FIGS. 1 and 2.

In the embodiment variant shown here the winding system 37 is not formed directly in the tool holder 19, 20 but a winding system mount 42 is provided into which the winding system 37 is inserted and which is mounted in turn in the tool holder 19, 20. The winding system mount 42 can be designed such that it improves the magnetic properties of the winding system 37. For example the winding system mount 42 can have an iron core 43 and with for example plastic outside the winding system 37.

Furthermore, it is possible to provide a sliding layer 44 on the tool holder 19, 20 by means of which the displacement of the bending tool 4 can be facilitated. In an alternative variant it is also possible for the sliding layer 44 to be arranged on the bending tool 4 and to function similarly to the shown embodiment variant. Instead of the sliding layer 44 a sliding bearing arrangement can also be provided.

FIG. 4 shows a further embodiment of a bending tool 4 and a corresponding tool holder 19, 20, wherein the same reference numerals and component names are used for the same parts as in the preceding FIGS. 1 to 3. To avoid unnecessary repetition reference is made to the detailed description of the preceding FIGS. 1 to 3.

As shown in FIG. 4 the winding system 37 can be arranged on a side face 45 of the receiving groove 34. Corresponding with this it is possible for the permanent magnets 39 to be arranged in a side face 46 of the receiving portion 35.

In a further not shown embodiment variant it is also possible for the winding system 37 to be arranged in both side faces 45 of the receiving groove 34 and for the permanent magnets 39 to be arranged in both side faces 46 of the receiving portion 35. The components are hereby preferably designed to be symmetrical relative to a central plane 47. Such an embodiment has the advantage that the magnetic forces can be cancelled in transverse direction 48 and it is thus possible to prevent high frictional forces between the bending tool 4 and tool holder 19, 20.

In particular, in such an embodiment the permanent magnets 39 and the winding system 37 can be arranged such that the bending tool 4 when activating the magnetic displacement or the magnetic force is lifted slightly in vertical direction so that the friction between the bending tool 4 and tool holder 19, 20 is reduced.

Furthermore, in all of the described embodiments a sensor 49 can be provided, which sensor 49 is used for detecting the position of the bending tool 4. The sensor 49 can be arranged in the tool holder 19, 20, wherein different bending tools 4 can be identified and detected by the sensor 49. The sensor can be designed for example as an optical sensor. Furthermore, it is also possible for the sensor to be designed as a proximity sensor, such as a Hall sensor.

In an alternative variant the sensor 49 can be arranged in the bending tool 4, in particular for example an incremental encoder is arranged in the tool holder 19, 20 which cooperates with the sensor 49.

FIG. 5 shows a further embodiment of a bending tool 4 and a tool holder 19, 20, wherein the same reference numerals and component names are used for the same parts as in the preceding FIGS. 1 to 4. To avoid unnecessary repetition reference is made to the detailed description of the preceding FIGS. 1 to 4.

As shown in FIG. 5 the driver device 41 can be designed in the form of a shuttle 50, which can be guided for example in the tool holder 19, 20. The guiding of the shuttle 50 in the tool holder 19, 20 can be performed for example by guide rollers 51 formed laterally on the shuttle 50. Furthermore, it is possible to arrange permanent magnets 39 for example on a lower side of the shuttle 50. The shuttle 50 can comprise for example one or more pins 52 which are designed for forming a form-fitting connection between the shuttle 50 and bending tool 4. In this way the bending tool 4 can be displaced by means of the shuttle 50 in the tool holder 19, 20.

In a further not shown embodiment variant the shuttle 50 can comprise an attachment and therefore is provided as a cleaning shuttle 53 for cleaning the receiving groove 34 of the tool holder 19, 20.

FIG. 6 shows a further embodiment of a bending tool 4 and a tool holder 19, 20, wherein the same reference numerals and component names are used for the same parts as in the preceding FIGS. 1 to 5. To avoid unnecessary repetition reference is made to the detailed description of the preceding FIGS. 1 to 5.

As shown in FIG. 6, it is possible that a clamping jaw 54 is formed in the bending tool 4, which clamping jaw 54 is used for clamping the bending tool 4 in the tool holder 19, 20. By clamping the bending tool 4 it is possible to prevent the bending tool 4 from sliding undesirably in longitudinal direction of the tool holder 19, 20. The clamping jaw 54 can be designed for example so that it is activated by the winding system 37. In this way the clamping applied by the clamping jaw 54 can be released when initiating the transverse movement of the bending tool 4.

Such a clamping system can be formed for example in that a clamping jaw 55 is provided which is arranged in the bending tool 4 and is pushed by means of a spring 56 against the tool holder 19, 20. The clamping jaw 55 can be disengaged by means of an actuator system 57.

The actuator system 57 can for example comprise a cable pull or a lever system which can be coupled to the permanent magnets or to another actuator element. Said actuator element can be activated by the winding system 37.

FIG. 7 shows a further embodiment of a bending tool 4 and a tool holder 19, 20, wherein the same reference numerals and component names are used for the same parts as in the preceding FIGS. 1 to 6. To avoid unnecessary repetition reference is made to the detailed description of the preceding FIGS. 1 to 6.

In the embodiment according to FIG. 7 the winding system 37 is arranged in an attachment strip 58. The attachment strip 58 can hereby be arranged on the surface of the tool holder 19, 20. In this connection a permanent magnet 39 can be arranged laterally on the bending tool 4. According to the already described embodiments the permanent magnet 39 can cooperate with the attachment strip 58 or with the winding system 7 arranged in the attachment strip 58.

An embodiment of this kind with an attachment strip 58 has the advantage that the attachment strip 58 if necessary can be retrofitted into an already existing tool holder 19, 20.

FIG. 8 shows a cross-section in longitudinal direction of the bending tool 4, wherein the same reference numerals and component names are used for the same parts as in the preceding FIGS. 1 to 7. To avoid unnecessary repetition reference is made to the detailed description of the preceding FIGS. 1 to 7.

As shown in FIG. 8 it is possible to arrange a plurality of permanent magnets 39 in a longitudinal extension of the bending tool 4.

The embodiments show possible embodiment variants of the production facility 1, whereby it should be noted at this point that the invention is not restricted to the embodiment variants shown in particular, but rather various different combinations of the individual embodiment variants are also possible and this variability, due to the teaching on technical procedure, lies within the ability of a person skilled in the art in this technical field.

Furthermore, individual features of combinations of features from the various shown and described embodiments can in themselves represent independent solutions according to the invention.

The underlying objective of the independent solutions according to the invention can be taken from the description.

All of the details relating to value ranges in the present description are defined such that the latter include any and all part ranges, e.g. a range of 1 to 10 means that all part ranges, starting from the lower limit of 1 to the upper limit 10 are included, i.e. the whole part range beginning with a lower limit of 1 or above and ending at an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1 or 5.5 to 10.

Mainly the individual embodiments shown in FIGS. 1, 2, 3, 4, 5, 6, 7, 8 can form the subject matter of independent solutions according to the invention. The objectives and solutions according to the invention relating thereto can be taken from the detailed descriptions of these figures.

Finally, as a point of formality, it should be noted that for a better understanding of the structure of the production facility 1, the latter and its components have not been represented true to scale in part and/or have been enlarged and/or reduced in size.

List of reference numerals 1 production facility 2 workpiece 3 bending press 4 bending tool 5 bending punch 6 bending die 7 machine frame 8 base plate 9 side panel 10 side panel 11 transverse cross-tie 12 front end face 13 first pressing bar 14 second end face 15 linear guide 16 second pressing bar 17 end face 18 end face 19 first tool holder 20 second tool holder 21 drive assembly 22 drive means 23 power network 24 control device 25 input terminal 26 spindle drive 27 adjusting means 28 recess 29 recess 30 insertion position 31 bending edge 32 parallel direction 33 length 34 receiving groove 35 receiving portion 36 linear motor 37 winding system 38 groove base 39 permanent magnet 40 end side 41 driver device 42 winding system mount 43 iron core 44 sliding layer 45 side face receiving groove 46 side face receiving portion 47 central plane 48 transverse direction 49 sensor 50 shuttle 51 guide roller 52 pin 53 cleaning shuttle 54 clamping jaw 55 clamping jaw 56 spring 57 actuator system 58 attachment strip 

1: A bending press (3), in particular press brake, comprising a machine frame (7) and pressing bars (13, 16) and tool holders (19, 20) arranged or formed on the pressing bars (13, 16) and bending tools (4) in the form of a bending punch (5) or a bending die (6), wherein a receiving portion (35) of the bending tools (4) is mounted in a receiving groove (34) of the tool holder (19, 20), wherein the tool holder (19, 20) and a driver device (41) assigned to the bending tool (4) is designed as a linear motor (36), whereby the bending tool (4) can be positioned in a direction (32) parallel to a bending edge (31). 2: The bending press as claimed in claim 1, wherein the tool holder (19, 20) is designed as a long stator. 3: The bending press as claimed in claim 1, wherein the driver device (41) is designed as a shuttle (50), which is guided in the tool holder (19, 20) and to which the receiving portion (35) of the bending tool (4) can be coupled. 4: The bending press as claimed in claim 3, wherein the shuttle (50) can be coupled by means of retractable pins (52) to the receiving portion (35) of the bending tool (4). 5: The bending press as claimed in claim 1, wherein the driver device (41) is designed in one piece with the receiving portion (35) of the bending tool (4). 6: The bending press as claimed in claim 1, wherein in the tool holder (19, 20) a cleaning shuttle (53) is arranged which is designed for cleaning the receiving groove (34) of the tool holder (19, 20), wherein the cleaning shuttle (53) also acts as a linear motor (36) with the tool holder (19, 20). 7: The bending press as claimed in claim 1, wherein permanent magnets (39) are arranged in the driver device (41). 8: The bending press as claimed in claim 1, wherein in the area of the receiving groove (34) of the tool holder (19, 20) a three-phase winding system (37) is arranged, wherein the winding system (37) is controlled by a control device (24) such that individual bending tools (4) mounted in the tool holder (19, 20) can be displaced independently of one another. 9: The bending press as claimed in claim 8, wherein the winding system (37) is arranged on a groove base (38) of the receiving groove (34) and the permanent magnets (39) are arranged on one end side (40) of the receiving portion (35) of the bending tool (4). 10: The bending press as claimed in claim 8, wherein the winding system (37) is formed on at least one side face (45) of the receiving groove (34) and the permanent magnets (39) are arranged on at least one side face (46) of the receiving portion (35) of the bending tool (4). 11: The bending press as claimed in claim 10, wherein the winding system (37) is formed on both side faces (45) of the receiving groove (34) and the permanent magnets (39) are arranged on both side faces (46) of the receiving portion (35) of the bending tool (4), wherein the two winding systems (37) are arranged to be symmetrical to a central plane (47) of the tool holder (19, 20). 12: The bending press as claimed in claim 8, wherein the winding system (37) extends over the whole length (33) of the tool holder (19, 20). 13: The bending press as claimed in claim 1, wherein a sensor (49) is formed which is provided for detecting the position of the bending tool (4). 14: The bending press as claimed in claim 13, wherein the sensor (49) is arranged on the tool holder (19, 20). 15: The bending press as claimed in claim 7, wherein in the bending tool (4) a clamping jaw (54) is formed which clamping jaw (54) can be released by the magnetic field of the winding system (37). 16: The bending press as claimed in claim 1, wherein the tool holder (19, 20) comprises an attachment strip (58) which is arranged outside the receiving groove (34) and in which the winding system (37) is integrated. 